The importance of the eggshell or chorion to an insect cannot be overstated. Among other things it facilitates sperm entry, protects the embryo and allows for gas exchange. Elucidation of chorionic molecular structure and its regulation has been the subject of detailed analyses for many years now in silkmoths and Drosophila. Unfortunately, studies on the molecular aspects of mosquito chorions have been neglected. One of the major objectives and specific aims of this proposal is to correct this oversight. We have succeeded in isolating Aedes chorions at all stages of ovarian development and have begun to characterize the individual proteins that constitute the chorion. Furthermore, we want to learn how these proteins are held together and investigate the possible role of hormones which may regulate their syntheses. A second objective is to continue our studies of a high affinity juvenile hormone binding protein (JHBP) which we have identified in A. aegypti and appears shortly after blood-feeding. Preliminary evidence indicates that the synthesis of this JHBP is regulated by a head factor. We plan to investigate this further. In addition, time permitting, further purification and characterization of this JHBP will be carried out in order to correlate its appearance with known endocrinological events in mosquitoes. Lastly, we wish to gain some insight into the physical and chemical mechanisms which regulate egg diapause in A. atropalpus. Experiments are suggested which will hopefully lead to the identification of an egg diapause factor in mosquitoes. Mosquitoes are important disease carrying vectors of worldwide significance. It is clear that the more we learn about their biology, the better our chances become of controlling them. Our long-range objectives are to determine what molecular factors regulate the reproductive physiology of Aedes mosquitoes, particularly A. aegypti. This knowledge can serve as a basis for the intelligent design of agents which can interrupt the reproductive cycle of these important disease vectors.